It has hitherto been known to use industrial robots, etc. to automatically feed workpieces to machine tools or to extract machined workpieces therefrom in order to achieve a continuous machining operation with the machine tools. However, it is a wellknown fact that this procedure has several disadvantages.
That is, in the conventional industrial robots, in order to prevent a wrist member mounted to the end of an arm and a hand member mounted to the wrist member, from relative movement therebetween so that the wrist member can perform an operation independently of the hand member, the arm must be provided near the wrist member with a differential gear. However, this makes the construction near the wrist member complicated, large and heavy so that problems arise with regard to maneuverability, safety and reliability. Further, since such industrial robots are required to be installed separately from the machine tools additional floor space is required for the robots and they may interfere with an operator's work such as the exchange of cutting tools, etc. Further the operational range of the robot partially overlaps with that of the operator so that questions in terms of safety in operation arise. Moreover, although it is necessary to alter the operation of the robot according to the shape, dimensions, etc. of a workpiece to be machined, the procedure for changing the robot's operation is very complicated and usually takes a considerable amount of time to achieve, even when carried out by a person familiar with the task.